This invention relates to a nozzle assembly for conducting molten metal to a die casting mold.
In die casting, a nozzle assembly is typically employed to conduct the molten metal under pressure from a molten metal source to a mold or die. To avoid solidification of the metal in the nozzle assembly and ensure proper filling of the mold, it is usual practice to heat the nozzle assembly by a flame. Flame heating, while satisfactory in some applications, embodies several disadvantages. Specifically, flame heating tends to be wasteful of energy, is not amenable to precise temperature control, and tends to promote tempering and resultant erosion of the metal lining the bore of the nozzle and a consequent short nozzle service life. Whereas attempts have been made to heat the nozzle assembly in a die casting apparatus by the use of an electrical resistance heating element, such arrangements have been generally unsatisfactory due to the inability to precisely control the temperature within the nozzle assembly.
Prior art nozzle assemblies have also suffered from rapid wear and distortion of the nozzle at the outlet or tip of the nozzle where the nozzle makes sealing contact with a spherical seat at the inlet of the mold sprue.
Prior art nozzle assembly designs have also not satisfied problems associated with freeze ups occurring at the outlet tip of the nozzle.